77720812061 has 16 divisors (see below), whose sum is σ = 78837183360. Its totient is φ = 76612784640.

The previous prime is 77720812051. The next prime is 77720812063. The reversal of 77720812061 is 16021802777.

It is a cyclic number.

It is not a de Polignac number, because 77720812061 - 2¹⁸ = 77720549917 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (77720812063) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 41361920 + ... + 41363798.

It is an arithmetic number, because the mean of its divisors is an integer number (4927323960).

Almost surely, 2^77720812061 is an apocalyptic number.

It is an amenable number.

77720812061 is a deficient number, since it is larger than the sum of its proper divisors (1116371299).

77720812061 is a wasteful number, since it uses less digits than its factorization.

77720812061 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3796.

The product of its (nonzero) digits is 65856, while the sum is 41.

The spelling of 77720812061 in words is "seventy-seven billion, seven hundred twenty million, eight hundred twelve thousand, sixty-one".